The invention relates to a harvesting machine for threshing and sorting seed plants such as grain, peas and turnip rapes. In the following specification, the treated plant is called grain, and the seeds respectively grains.
Traditionally there are two types of harvesting machines. In the older type, the machine is provided with a threshing roller transversal to the proceeding direction, which roller separates the grains from the spikes. After the threshing roller, the grain-straw mass is conveyed onto the beaters or flails provided after the roller, which flails separate the straw from the grains by utilizing gravitational force. From these flails, the grains are conveyed onto horizontal sieves, where the grains are cleaned by means of gravity and blowing. In the newer machine type, the threshing roller is an elongate, rotating drum, and the separation of grains from the straw takes place at the rear of this drum and by means of gravity. From the drum, the grains are transported onto the sieves in a similar fashion as in the older machines. The drawback of these machines is that the cutting, sorting and cleaning devices are installed successively, which leads to a large size and particularly to a considerable length in the combination.
In the prior art there is known a threshing apparatus introduced in the U.S. Pat. No. 4,274,426, which represents the above described newer machine type. The harvesting, i.e. the cutting and sorting of the grains, is arranged to take place in a rotating threshing and separating cylinder which is installed horizontally in the lengthwise direction. The threshing and separating are carried out by the action of centrifugal force. The grains are sieved and cleaned separately after the threshing and sorting. This kind of apparatus takes up a lot of space and is cumbersome in construction.
An example of harvesting machines provided with pedestal bearings is introduced in the U.S. Pat. No. 2,905,182, in which machine the sieve set is arranged to be rotatable. This sieve set, however, is small in area and is placed in the top part of the harvesting machine. In addition to this, the sieve set is geared so that the straw mass has to pass in between both the stationary and the moving support arms, which brings forth a danger of blocking of the machine.